2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2019-2020 Rubicon Communications, LLC (Netgate)
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
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30 #ifndef _CURVE25519_H_
31 #define _CURVE25519_H_
33 #include <sys/systm.h>
35 #define CURVE25519_KEY_SIZE 32
37 void curve25519_generic(u8 [CURVE25519_KEY_SIZE],
38 const u8 [CURVE25519_KEY_SIZE],
39 const u8 [CURVE25519_KEY_SIZE]);
41 static inline void curve25519_clamp_secret(u8 secret[CURVE25519_KEY_SIZE])
44 secret[31] = (secret[31] & 127) | 64;
47 static const u8 null_point[CURVE25519_KEY_SIZE] = { 0 };
49 static inline int curve25519(u8 mypublic[CURVE25519_KEY_SIZE],
50 const u8 secret[CURVE25519_KEY_SIZE],
51 const u8 basepoint[CURVE25519_KEY_SIZE])
53 curve25519_generic(mypublic, secret, basepoint);
54 return timingsafe_bcmp(mypublic, null_point, CURVE25519_KEY_SIZE);
57 static inline int curve25519_generate_public(u8 pub[CURVE25519_KEY_SIZE],
58 const u8 secret[CURVE25519_KEY_SIZE])
60 static const u8 basepoint[CURVE25519_KEY_SIZE] __aligned(32) = { 9 };
62 if (timingsafe_bcmp(secret, null_point, CURVE25519_KEY_SIZE) == 0)
65 return curve25519(pub, secret, basepoint);
68 static inline void curve25519_generate_secret(u8 secret[CURVE25519_KEY_SIZE])
70 arc4random_buf(secret, CURVE25519_KEY_SIZE);
71 curve25519_clamp_secret(secret);
74 #endif /* _CURVE25519_H_ */